Prolapsed mitral valve prolapse (PMV) is classically associated with disorders of ventricular excitability whose significance is unclear. However,
syncope can suggest the possibility of a serious ventricular
arrhythmia. The objective of this study was to try to identify the mechanisms of
dizziness and
syncope associated with PMV. We report the results of programmed atrial and ventricular stimulation performed under baseline conditions and after administration of
Isuprel in 56 patients with PMV: 27 patients had a history of
presyncope or
syncope (group I), 14 had spontaneous atrial or
supraventricular tachycardias without
dizziness or
syncope (group II) and 15 were asymptomatic and investigated for VEBs or conduction disorders (group III). The following results were obtained: In group I, 6 patients experienced sustained inducible
ventricular tachycardia (VT); an atrial
tachycardia (atrial
tachycardia and/or
atrial fibrillation) (AT) was also induced in 5 of them. In another 19 patients, a
supraventricular tachycardia (SVT) and/or AT was induced. A total of 24 atrial or junctional
tachycardias were triggered in this group. In group II, AT and/or SVT were reproduced in 13 out of 14 cases (93%). In group III, AT was triggered in 3 patients (20%). SVT were induced by
Isuprel while AT were triggered prior to administration of
Isuprel, under baseline conditions, and 3 of them were reproduced during vagal manoeuvres. A ventricular arrhythmogenic effect was observed in two cases in group II while taking class I antiarrhythmics. In conclusion, spontaneous AT and SVT of PMV are easily inducible with a sensitivity of 93%, but are difficult to induce in asymptomatic subjects. The high incidence of TA and SVT in the case of unexplained
presyncope in subjects without documented
tachycardia therefore appears to be suggestive of a relationship between these
presyncopes and AT or SVT. However, the search for VT should take precedence. SVT appear to be catecholaminergic while AT tend to be vagal.